The present invention relates generally to electrical power systems, and in particular to an integrated power unit for storing and supplying power to electrical systems on-board an aircraft.
Typical aircraft systems employ several sources of electrical power, each source providing a particular utility during different stages of flight. For instance, an aircraft may employ batteries, an integrated power pack (IPP), and main engines for generation of electrical power. In a typical system, the batteries supply electrical power to the IPP when the aircraft is on the ground. The IPP uses the electrical energy provided by the battery to rotate turbomachinery associated with a gas turbine engine to speeds sufficient for light-off of the gas turbine. Following light-off, the gas turbine associated with the IPP is accelerated to a self-sustaining speed at which point battery power is removed. Rotational energy provided by the combustion of the gas turbine is converted to electrical energy by a generator and distributed to electrical loads associated with the aircraft. In particular, electrical energy provided by the IPP is typically employed to provide starting power to the main engines. Electrical energy provided by the IPP is converted by a motor to rotational energy that is used to accelerate the main engine to speeds sufficient for light-off of the main engine. Following successful light-off of the main engine, the IPP may be shut-down, with a generator coupled to the main engine providing the electrical energy consumed by the aircraft.
In addition to these desired sources of power, many aircraft employ electrical loads that may contribute electrical energy to the distribution system. Electric motors used to convert electrical energy provided by the distribution system to mechanical energy to drive a mechanical load, such as aircraft flight control surfaces, may themselves be driven by the load such that the motor operates as a generator and provides electrical energy back onto the distribution bus. The electrical energy provided by some of the loads may result in substantial spikes in voltage provided onto the distribution bus. Typical systems dissipate this excess electrical power by converting it to heat. It would be beneficial if this excess energy could be stored rather than merely dissipated.